The disclosure relates to a radial piston machine as per the description below and to a piston suitable for a radial piston machine.
A radial piston machine of said type and a piston of said type are known for example from DE 39 19 456 C2. Said document discloses a radial piston machine having a stroke ring which is fixed with respect to a housing and which may for example be arranged with a cam path or eccentrically with respect to a rotatably mounted cylinder star. In the cylinder star, a multiplicity of pistons is guided so as to be displaceable in the radial direction, said pistons being supported on the stroke ring in each case by means of a roller. In the known solutions, said roller is rotatably mounted on the piston foot via a bearing shell, wherein captive retention of the piston is realized by virtue of the fact that the piston foot extends around the roller over more than 180°, such that the roller is secured in the radial direction. A problem of said solution is that considerable outlay is required for the machining of the piston foot, because the embracing configuration of the piston foot cannot be realized by means of simple grinding, but rather must be formed by means of transverse milling or stamping. Such production methods are relatively imprecise, such that a precise bearing shell fit in the piston foot cannot be ensured. In the worst case, bearing shell fracture may occur.
A similar embodiment of a piston foot is also disclosed in DE 39 26 185 C2. In said variant, too, the roller 1 is secured by an embracing form of the piston foot.
US 2009/0183629 A1 presents a piston in which the embracing form is realized not by means of a cutting-type machining process but rather by means of a crimping process. In one variant, in said known piston arrangement, the bearing shell also extends around the roller over more than 180°—all of said solutions however require that the piston foot be of crimpable configuration. As a result of the required crimping, the production outlay is likewise considerable, wherein a crimped securing arrangement necessitates the provision of a suitable piston material, such that there are certain restrictions with regard to material selection.
By contrast, it is the object of the disclosure to provide a radial piston machine and a piston which is suitable for such a radial piston machine, in which a roller is captively retained in a simple manner.
Said object is achieved, with regard to the radial piston machine, by means of the features described below, and with regard to the piston, by means of the features of the coordinate description below.
The description below relates to advantageous refinements of the disclosure.